Synthesis of N-fused dithia and dibenzi homoporphyrins

Abstract

N-Fused dithia and dibenzi homoporphyrins have been synthesized using a [2 + 2] approach by condensing one equivalent of appropriate dithienyl/di p-phenylene ethene diol with one equivalent of N-confused dipyrromethane in CH₂Cl₂ under mild acid catalysed conditions. The X-ray structure obtained for the N-fused dibenzi homoporphyrin revealed that the fused tripentacyclic ring was planar and was tilted by an angle of 11.35° whereas the p-phenylene moieties were highly deviated by angles of 48.70° and 50.93° from the mean plane defined by five meso carbon atoms. The NMR and absorption features suggested the non-aromatic nature of both N-fused dithia and dibenzi homoporphyrins. The DFT studies revealed that the N-fused dithia homoporphyrin was highly distorted with one thiophene ring facing outside the macrocyclic cavity. The spectral features of both N-fused dithia and dibenzi homoporphyrins were supported by TD-DFT studies.